We Keep Coding

Sending data from Django view to Django form

I have a Django view and I want to send the request data to a form.
class PostDetailView(DetailView):
model = Post
form = CommentForm
def get_form_kwargs(self):
kwargs = super(PostDetailView, self).get_form_kwargs()
kwargs['user'] = self.request.user.username
return kwargs
def post(self, request, *args, **kwargs):
form = CommentForm(request.POST)
if form.is_valid():
post = self.get_object()
form.instance.user = request.user
form.instance.post = post
form.save()
return redirect(reverse("post-detail", args=[post.pk]))
from django import forms
from .models import Comment
from djrichtextfield.widgets import RichTextWidget
class CommentForm(forms.ModelForm):
user = forms.ChoiceField(required=True)
def __init__(self, *args, **kwargs):
self.user = kwargs.pop('user', None)
super(CommentForm, self).__init__(*args, **kwargs)
self.fields['user'].choices = self.user
content = forms.CharField(widget=RichTextWidget(attrs={
'class': 'md-textarea form-control',
'placeholder': 'Comment here ...',
'rows': '4',
}))
class Meta:
model = Comment
fields = ('author', 'content',)
<form method="POST" href="{% url 'post-detail' post.id %}">
{% csrf_token %}
<div class="form-group">
{{form | safe}}
</div>
<button class="btn btn-primary btn-block" type="submit">Comment</button>
</form>
urlpatterns = [
path('post/<int:pk>/', PostDetailView.as_view(), name="post-detail"),
]
According to the docs, get_form_kwargs allows key-value pairs to be set in kwargs. The kwargs is then passed into the form. The form's init function should then be able to pick up the user value from kwargs.
However, self.user returns None, and debugging showed that get_form_kwargs did not run at all.
I have two questions: how do functions in view classes get executed? And what is the correct method to pass data from a view to a form?
EDIT
I have refactored the comment feature into another view.
class AddCommentView(UpdateView):
model = Post
form = CommentForm
def post(self, request, *args, **kwargs):
form = CommentForm(request.POST)
if form.is_valid():
post = self.get_object()
form.instance.user = request.user
form.instance.post = post
form.save()
return redirect(reverse("post-detail", args=[post.pk]))
def get_form_kwargs(self):
kwargs = super(PostDetailView, self).get_form_kwargs()
kwargs.pop('instance', None)
kwargs['user'] = self.request.user.username
return kwargs
<form method="POST" href="{% url 'add-comment' post.id %}">
{% csrf_token %}
<div class="form-group">
{{form | safe}}
</div>
<button class="btn btn-primary btn-block" type="submit">Comment</button>
</form>
urlpatterns = [
path('post/<int:pk>/', AddCommentView.as_view(), name="add-comment")
]
However UpdateView cannot handle POST requests (405).

It's not explicitly described in the docs but get_form_kwargs is only triggered with a CreateView or an UpdateView.
In your case you can use UpdateView, and then use form_valid to do your post process. But note that we need to delete kwargs['instance'], because by default this view will think we are working with a Post object when in fact it's a Comment:
Try with this:
class PostDetailView(UpdateView):
model = Post
form = CommentForm
def get_form_kwargs(self):
kwargs = super(PostDetailView, self).get_form_kwargs()
# Remove the post object as instance,
# since we are working with a comment
kwargs.pop('instance', None)
kwargs['user'] = self.request.user.username
return kwargs
def form_valid(self, form):
instance = form.save(commit=False)
instance.user = self.request.user
instance.post = self.get_object() # returns the post
instance.save()
return redirect(reverse("post-detail", args=[post.pk]))
or if you don't want to use UpdateView (not recommended), you can just explicitly call get_form_kwargs when you build your form. You cannot call super().get_form_kwargs() though, since as discussed the parent class doesn't have this method:
class PostDetailView(DetailView):
model = Post
form = CommentForm
def get_form_kwargs(self):
kwargs = {'user': self.request.user.username}
return kwargs
def post(self, request, *args, **kwargs):
form = CommentForm(request.POST, **self.get_form_kwargs())
if form.is_valid():
post = self.get_object()
form.instance.user = request.user
form.instance.post = post
form.save()
return redirect(reverse("post-detail", args=[post.pk]))
Lastly, do consider renaming this class, since we are working with adding a comment to post, and not really about "post detail", so something like PostAddCommentView?

My view doesn't save the instance from Form in Djagno

I'm trying make a comment section for my Q&A project.I made the model for comment , the form part in question_detail.html an , also the QuestionCommentForm() in form.py .
model.py
class QuestionComment(models.Model):
user = models.ForeignKey(User,on_delete=models.CASCADE)
question =
models.ForeignKey(Question,on_delete=models.CASCADE)
created_date = models.DateTimeField(auto_now_add= True)
body = models.CharField(max_length=200, null= True ,
blank = True, default ='')
def __str__(self):
return str(self.body)
forms.py
{%if c_form%}
<form method="POST" action= "{% usl 'blog:question-commet' question.id >{% csrf_token %}
{{c_form.media}}
{{ c_form.as_p}}
<button type = "submit" , name = "question_id", value = "{{question.pk}}", class ="btn btn-secondary btn-sm">submit comment</button>
views.py
#api_view(['POST','GET'])
def question_comment(request, *args, **kwargs):
form = QuestionCommentForm()
print('finction comment started'*20)
if request.method == 'POST':
c_form = QuestionCommentForm(request.POST)
if c_form.is_valid():
new_comment = c_form.save(commit=False)
new_comment.refresh_from_db()
c_form.instance.user = request.user
question = Question.objects.get(id = request.POST.get('question_id')
new_comment.question = question
new_comment.bldy =c_form.cleaned_data.get('body')
new_comment.save()
context['c_form'] = c_form
return render(request, 'blog/question_detail.html',context)
class QuestionDetail(DetailView):
template_name = 'blog/question_detail.html'
model = Question
context_object_name = 'question'
count_hit = True
def get_queryset(self):
return Question.objects.filter(id = self.kwargs['pk'])
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
c_form = QuestionCommentForm()
context = super(QuestionDetail,self).get_context_data(**kwargs)
self.obj= get_object_or_404(Question, id = self.kwargs['pk'])
self.object.save()
self.object.refresh_from_db()
answers = Answer.objects.filter (question_id = self.obj.id).order_by('-created_date')
liked =self.obj.like.filter(id =self.request.user.id).exists()
print('liked in class question not checked still' *10)
comments= QuestionComment.objects.filter(question = self.kwargs['pk'])
context['comments']= comments
context["answers"]=answers
context["liked "] = liked
context['c_form'] = c_form
return context
def post(request, *args, **kwargs):
print('post started'*100)
c_form = QuestionCommentForm()
c_form = QuestionCommentForm(request.POST)
if c_form.is_valid():
new_comment = c_form.save(commit=False)
new_comment.refresh_from_db()
new_comment.user = request.user
new_comment.question = c_form.cleaned_data.get('question_id')
new_comment.bldy =c_form.cleaned_data.get('body')
new_comment.save()
context['c_form'] = c_form
else:
c_form= QuestionCommentForm()
return render(request, 'blog/question_detail.html',context)
url.py
...
path('question-comment/<int:pk>/', question_comment, name = 'question-comment'),
]
in my view, first I tried to use a another function to handle the comment, got no result and made a def post()
in the class QuestionDetial() , and still the form shows up but when I type something and hit the button , it refresh the page and nothing saves . I have already saved a comment using admin and it appears in the question-detail page. used print to find the bug, but it seems the post() in class and the question_comment() not being recall. searched a lot but no answer. (BTW I get no error except the NoReverseMatch that I fixed)

You never save the model object (not by the form, nor by the view). Furthermore the name of the method is 'POST', not 'Post':
#api_view(['POST','GET'])
def question_comment(request, *args, **kwargs):
form = QuestionCommentForm()
print('finction comment started'*20)
if request.method == 'POST':
c_form = QuestionCommentForm(request.POST)
if c_form.is_valid():
c_form.instance.user = request.user
c_form.save()
context = {'c_form': c_form }
return render(request, 'blog/question_detail.html',context)

ok , the problem was that I had two form-tags in question_detail template and buy adding comment form in the end of the template had 3 , but the problem was when I pressed the submit comment button the terminal showed this message
"POST /create-like/blog/answer/18/ HTTP/1.1" 302 0
which was the form I had made for like function .(while my url was question-comment)
I accidentally forgot to close the like-form tag in template. so all I needed was putting a
</form>
after the form block .
thank's Willem Van Onsem. it solved my post method error.
and these were very helpful
Proper way to handle multiple forms on one page in Django
How can I build multiple submit buttons django form?

How to get the content from my database in views.py? [Django]

I am trying to print the content fields from my database,
Here's my models.py file:
class Post(models.Model):
title = models.CharField(max_length=100)
content = models.TextField()
read_time = models.TimeField(null=True, blank=True)
view_count = models.IntegerField(default=0)
Here's my views.py file:-
class PostDetailView(DetailView):
model = Post
def get_object(self):
obj = super().get_object()
obj.view_count += 1
obj.save()
return obj
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
all_texts = {
'texts': context.content
}
print(all_texts[texts])
return context
I am trying to access all the data's from the content field from my database,
But the above way is not working, Is there any way I can access all the data's from the content field, because I have to perform some action on these fields, like calculate the read_time of any content, based on the length of it.

You do not have to override the .get_queryset(…) method [Django-doc] for that, since the object is already passed to the context. You can simply render it in the template with:
{{ object.content }}
In case you really need this in the context, you can implement this as:
class PostDetailView(DetailView):
model = Post
# …
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context.update(
texts=self.object.content
)
return context
In case you need all post objects, you can add these to the context:
class PostDetailView(DetailView):
model = Post
# …
def get_context_data(self, **kwargs):
context = super().get_context_data(**kwargs)
context.update(
texts=self.object.content,
posts=Post.objects.all()
)
return context
and render these as:
{% for post in posts %}
{{ post.content }}
{% endfor %}
It might be better to work with an F expression [Django-doc] when incrementing the view counter to avoid race conditions:
class PostDetailView(DetailView):
model = Post
def get_object(self):
obj = super().get_object()
views = obj.view_count
obj.view_count = F('view_count') + 1
obj.save()
obj.view_count = views+1
return obj

Just query all objects and loop the queryset to manipulate them according to your needs like so:
def your_view(self, **kwargs):
# Get all table entries of Model Post
queryset = Post.objects.all()
# Loop each object in the queryset
for object in queryset:
# Do some logic
print(object.content)
[...]
return (..., ...)

first import models
from . models import Post
then in your function
data=Post.objects.values('content').all()
Now data have all the values in content field
data=[{'content':first_value},{'content':second_value},..like this...]

In Django REST Framework, how to get the "query parameter" sent by the previous page's hidden input?

I have an html page for listing the model "Descriptions", and at the end of it there's a button to go to the Description creation page, while sending the "character_id" that is intended to be a default initial value for the new Description (and I have set up the context so that the character_id would be there:
<!--The code for listing the Descriptions-->
<form action="{% url 'polls:description_detail_create_from_character' %}">
<input type="hidden" value="{{ serializer.context.character_id }}" name="character_id">
<input type="submit" value="New Description"/>
</form>
On the browser, if I click "New Description", it will bring me to:
http://localhost:8000/polls/description_detail_create_from_character/?character_id=3
However, then I don't know how can I get this "character_id" from description_detail_create_from_character (the next page)'s template. Thought it could be request.query_params.get('character_id', None), but doesn't work.
By debugging, I can find the dict query_params, however, there's nothing in it.
Just don't know how can I get this character_id=3. It's nowhere to be found in the {% debug %} either.
Is something more to be done in the Serializer?
Or View?
Is this ?character_id=3 here actually a query parameter here? If it is not then what it is?
Code:
Serializers.py:
# The serializer for the creation page
class DescriptionCreateFromCharacterSerializer(DescriptionSerializer):
author = serializers.HiddenField(default=serializers.CreateOnlyDefault(DefaultFieldCurrentUser())) # This works btw, unlike the next one
character = serializers.HiddenField(default=serializers.CreateOnlyDefault(DefaultFieldData(param_class=Character, param_key_field_name='character_id')))
class Meta:
model = Description
fields = ['character', ...other fields]
# The helper class
class CustomDefaultField(object):
def set_context(self, serializer_field):
# setting field "type", calculated by other serializer fields
self.request = serializer_field.context['request']
class DefaultFieldCurrentUser(CustomDefaultField):
def __call__(self):
return self.request.user
class DefaultFieldData(CustomDefaultField):
def __init__(self, **kwargs):
self.param_class = kwargs['param_class']
self.param_key_field_name = kwargs['param_key_field_name']
def __call__(self, **kwargs):
key_value = self.request.query_params.get(self.param_key_field_name, None)
if key_value:
obj = get_object_or_None(self.param_class, id=key_value) # Always id for now
if obj:
return obj
# Omitting some exception handling/assertion
views.py:
# The view for the create page
# Has a couple of hierarchy but I inlined all relevant/my stuff together
class DescriptionDetailCreateFromCharacterView(generics.CreateAPIView):
permission_classes = [polls.permissions.NovelUserPermission]
renderer_classes = [TemplateHTMLRenderer]
url_to_redirect_reverse = ''
def get(self, request):
serializer = self.get_serializer()
return Response({'serializer': serializer})
def post(self, request):
serializer = self.get_serializer(data=request.data)
if serializer.is_valid():
serializer.save()
if not self.url_to_redirect_reverse:
return Response({'serializer': serializer}, status=status.HTTP_201_CREATED)
else:
return redirect(django.urls.reverse_lazy(self.url_to_redirect_reverse))
else:
return Response({'serializer': serializer}, status=status.HTTP_400_BAD_REQUEST)
def get_serializer_class(self):
return self._writable_serializer
_model_class = Description
_writable_serializer = DescriptionCreateFromCharacterSerializer
_data_name_single = 'description'
_data_name_plural = 'descriptions'
template_name = 'polls/description_detail_create_from_character.html'
url_to_redirect_reverse = 'polls:character_description_list.html'
def get_queryset(self):
return self.model_class.objects.all()

Issue with Django form POST method

I am having a problem with the following view and form. The form loads correctly however when I edit any of the fields it does not save. After a bit of debugging I think it is due to one of two things: either request.method == "POST" is evaluating to false, or form.is_valid() is evaluating to false. So potentially something wrong with my template or my clean() method? I've searched previous questions and can't find anything that helps. I've also checked my clean() method against the Django docs and think it is OK.
views.py
#login_required
def edit_transaction(request, pk):
transaction = get_object_or_404(Transaction, pk=pk)
if request.method == "POST":
form = TransactionForm(request.POST, instance=transaction)
if form.is_valid():
transaction = form.save(commit=False)
transaction.updated = timezone.now()
transaction.save()
return redirect('view_transaction_detail', pk=transaction.pk)
else:
form = TransactionForm(request=request, instance=transaction)
return render(request, 'budget/new_transaction.html', {'form': form})
forms.py
class TransactionForm(forms.ModelForm):
class Meta:
model = Transaction
fields = ('title', 'transaction_type', 'category', 'budgeted_amount', 'actual_amount', 'date', 'comments',)
#new_category field to allow you to add a new category
new_category = forms.CharField(max_length=30, required=False, label="New Category Title")
def __init__(self, request, *args, **kwargs):
super(TransactionForm, self).__init__(*args, **kwargs)
#category is now not a required field because you will use category OR new_category
self.fields['category'].required=False
#set to allow use of self.request.user to set user for category
self.request = request
def clean(self):
category = self.cleaned_data.get('category')
new_category = self.cleaned_data.get('new_category')
if not category and not new_category:
# raise an error if neither a category is selected nor a new category is entered
raise forms.ValidationError('Category or New category field is required')
elif not category:
# create category from new_category
category, created = Category.objects.get_or_create(title=new_category, defaults={'user': self.request.user})
self.cleaned_data['category'] = category
return super(TransactionForm, self).clean()
template
{% extends 'budget/base.html' %}
{% block content %}
<h2>New transaction</h2>
<h4>To add a new category, leave Category blank and enter your new category in the New Category Title field</h4>
<form method="POST" class="post-form">
{% csrf_token %}
{{ form.as_p }}
<button type="submit" class="save btn btn-default">Save</button>
</form>
{% endblock %}
update following answer - accessing request through kwargs
def __init__(self, *args, **kwargs):
super(TransactionForm, self).__init__(*args, **kwargs)
self.fields['category'].required=False
self.request = kwargs.pop('request', None)

As I mentioned on your last question, since you've changed the signature of the form's init method you need to pass the request both times you instantiate it. You're only doing so when it is not POST; so, when it is a POST, Python takes the data that you passing and assigns it to the request argument, leaving the data itself blank.
form = TransactionForm(request, data=request.POST, instance=transaction)
Note it is precisely for this reason that is is a bad idea to change the signature; instead, pass request as a keyword argument and inside the method get it from kwargs.